I realized a few days back, that if I send some bitcoins to someone, then it shows in blockchain an extra amount sent to my own wallet. So if I send 0.5 BTC from wallet A to B then blockchain shows

A--> B 0.5
A-->A 1 (basically sending it to my wallet as well.)

Today I noticed a different wallet address during a transaction. So it was like

A--> B 0.2
A--> C 0.5

Checking address C on blockchain, it gets sent back to A in some time. But since this morning, the bitcoins haven't come back to A. If I open my wallet on multibit, it shows the correct balance. However on blockchain, it's 0.5 less. The funds from C have not been sent back to A, but it shows on multibit the right balance in A.